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The Lansberg's hognose pitviper, Porthidium lansbergii lansbergii, inhabits northern Colombia. A recent proteomic characterization of its venom (J. Proteomics  114, 287–299) revealed the presence of phospholipases A2 (PLA2) accounting for 16.2% of its proteins. The two most abundant PLA2s were biochemically and functionally characterized. Pllans-I is a basic, dimeric enzyme with a monomer mass of 14,136 Da, while Pllans-II is an acidic, monomeric enzyme of 13,901 Da. Both have Asp49 in their partial amino acid sequences and, accordingly, are catalytically active upon natural or synthetic substrates. Nevertheless, these two enzymes differ markedly in their bioactivities. Pllans-I induces myonecrosis, edema, and is lethal by intracerebro–ventricular injection in mice, as well as cytolytic and anticoagulant in vitro. In contrast, Pllans-II is devoid of these effects, except for the induction of a moderate edema. In spite of lacking myotoxicity, Pllans-II enhances the muscle damaging action of Pllans-I in vivo. Altogether, results further illustrate the divergent functional profiles of basic and acidic PLA2s in viperid venoms, and suggest that Pllans-I plays a myotoxic role in envenomings by P. l. lansbergii, whereas Pllans-II, apparently devoid of toxicity, enhances muscle damage caused by Pllans-I.Two novel phospholipases A2 were isolated from Porthidium l. lansbergii venom.They belong to the acidic and basic Asp49-PLA2 groups, respectively.They a markedly different profile of activities.Toxicity is associated with the basic enzyme but not the acidic one.